CH4 - Amines

?
All amines have the group...
NH2
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Primary aliphatic amines can be formed in 2 different ways. What are these two reactions?
1. Nucleophilic substitution with halogenoalkanes. 2. Reduction of nitriles
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Nuclephilic substitution of halogenoalkanes - conditions?
Ammonia, sealed tube, 100'C, aqueous OR alcoholic conditions.
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Nuclephilic substitution of halogenoalkanes - what occurs first?
The halogenoalkane will react with the ammonia to form an ammonium salt.
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What happens next?
The ammonium salt will react with excess ammonia to form an aliphatic amine and an ammonium halide (e.g. chloride, NH4+Cl-)
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Why is the reaction between a halogenoalkane and ammonia described as nucleophilic substitution?
The carbon-halogen bond is polarised. The carbon atom attracts a lone pair of electrons from the +NH3.
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The reduction of nitriles - conditions?
Lithium aluminium hydride dissolved in ethoxyethane.
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When writing the equation for the reduction of nitriles, what number goes in front of the [H]?
4[H]
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How could you separate an amine from a nitrile?
An amine acts as a base - it could be treated with dilute acid to form an ammonium salt. This would cause an organic and aqueous layer to form. This can then be separated.
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Formation of aromatic amines from nitrobenzenes - conditions?
Tin and concentrated HCl.
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When writing the equation for the formation of aromatic amines from nitrobenzenes, what number goes in front of the [H]?
6[H]
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Explain the basicity of aliphatic amines.
The nitrogen atom has a lone pair of electrons. The alkyl groups 'push' electrons slightly towards the nitrogen atom, making it more ∂-. Therefore, the lone pair on the nitrogen is enriched, attracting protons more strongly.
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Explain the basicity of aromatic amines.
The nitrogen atom has a lone pair of electrons. The nitrogen lone pair can delocalise and become part of the delocalised pi e- system, making the nitrogen relatively less ∂-. However, this makes phenyl amine more susceptible to electrophilic sub.
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Which is the strongest base - ammonia, an aliphatic amine or an aromatic amine?
STRONGEST = aliphatic amine. WEAKEST = aromatic amine.
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Ethanoylation of primary amines - conditions?
Ethanoyl chloride and room temperature.
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Primary amines and cold nitric acid - conditions?
Cold nitric acid and temperature < 10'C
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Aromatic amines and nitric acid - what happens if the temperature above 10'C?
The benzenediazonium ion will decompose to form an alcohol and evolve N2, similar to that with aliphatic amines.
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Aromatic amines and nitric acid - what happens if the temperature is below 10'C?
The benzenediazonium ion is produced.
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A diazonium salt reacts with another compound containing a...
benzene ring called a coupling agent.
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What is an azo bridge?
N=N
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Coupling reactions - conditions?
Temperature < 10'C and alkaline solution (NaOH).
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Difference between an amine and an amide?
An amide has a C=O group alongside its NH2.
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Define a base.
An electron pair donor/proton acceptor.
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Define an acid.
An electron pair acceptor/proton donor.
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Other cards in this set

Card 2

Front

Primary aliphatic amines can be formed in 2 different ways. What are these two reactions?

Back

1. Nucleophilic substitution with halogenoalkanes. 2. Reduction of nitriles

Card 3

Front

Nuclephilic substitution of halogenoalkanes - conditions?

Back

Preview of the front of card 3

Card 4

Front

Nuclephilic substitution of halogenoalkanes - what occurs first?

Back

Preview of the front of card 4

Card 5

Front

What happens next?

Back

Preview of the front of card 5
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